A storage apparatus, such as a magnetic disk drive or a solid-state drive (SSD), generally comprises a host interface. One known magnetic disk drive is a hard disk drive (HDD). The host interface controls data transfer between a host and a storage device. Between the host interface and storage device, there is provided a buffer which temporarily stores data transferred between the host and storage device. Data transfer between the host interface and buffer is known as buffer transfer. Data transfer between the host and host interface is known as frame transfer because data is transferred using frames.
Suppose, in the conventional art, data specified by a data transfer command, such as a read command, given by the host to the storage apparatus is read from the storage device of the storage apparatus and transferred via the buffer. That is, suppose buffer transfer corresponding to the data transfer command from the host is activated. The conventional art is not based on the assumption that, when buffer transfer corresponding to a certain data transfer command has been activated, buffer transfer corresponding to another data transfer command is inserted by the time when the execution of the data transfer command has been completed.
Therefore, in the conventional art, when the execution of the data transfer command is being delayed, buffer transfer corresponding to another data transfer command is forced to wait. This results in a decrease in the efficiency of buffer transfer.